Write once recording is a means of securing information at a particular point in time, which information may be archived for future reference. Some recording media is inherently write once, such as “WORM” (write once, read many) optical disk media. As an example, WORM optical disk media may comprise an ablative material, which is ablated when written, and is therefore not subject to being erased and overwritten by new information. It is, however, subject to being destroyed if an attempt is made to overwrite previously written information. Other examples of write once optical disk recording media comprise non-reversible phase change and dye polymer WORM optical disk media. Thus, checks, such as microcode interlocks in a write-once optical disk drive, are employed to insure that a portion of a WORM optical disk that has been written is not overwritten and destroyed. Although the information may be destroyed, such as by ablating or distorting the media, the optical disk cannot be tampered with to alter the information by one with normal user resources.
Some media, such as magnetic tape, is inherently rewritable, meaning that prior information can be erased and overwritten by new information. Various “write protect” devices are often employed to theoretically protect written data on the inherently rewritable media from being erased or overwritten. One example comprises the write protect tab on video tape cartridges which may be broken off to expose an opening that is sensed by the tape drive which prevents erasure or overwriting the tape. Another example is the write protect thumb wheel or slide on magnetic tape cartridges, such as the IBM 3590 magnetic tape cartridge, which may be rotated or repositioned to a write protect position at which a tape data storage drive in which the cartridge is loaded will not erase or overwrite the tape media. An example of a write protect sliding notch is illustrated in U.S. Pat. No. 6,134,066. The patent allows a cartridge memory to be updated even though the cartridge media is write protected. Still another approach is to provide a write prevention flag in a tape information area of the tape, such as illustrated in U.S. Pat. No. 5,493,455.
However, should someone wish to tamper with the cartridge and media to alter the data, a covering may be placed over the write protect opening, or the write protect thumb wheel or slide may simply be rotated or repositioned away from the write protect position. Further, a data storage drive may be operated to reset a write prevention flag off. Thus, someone with normal user resources and an intention of erasing or altering data may easily do so, and then may again set the write protect back to the protected position or state, leaving an impression that the original data remains intact.
Another possibility is to provide write once cartridges that have special mechanical aspects which interface with specially designed data storage drives. Although it is more difficult to alter such a cartridge to read/write, such cartridges must be separately maintained for identification and used only in the instance that the data to be stored is desired to be stored at a write once cartridge. As the result, the write once cartridges are less easily employed by a user in a mixed cartridge environment.